References.—Comptes Rendus, séance, 1838; Memorial of Joseph Henry, 1880, p. 224; Ed. Highton, the El. Tel., 1852, pp. 38 and 43; “Appleton’s Encyclopædia,” 1871, Vol. XV. p. 335; De Bow’s Review, Vol. XXV. p. 551; Voigt’s Magazin, etc., Vol. XI. part iv. p. 61; Sc. Am. Supp., No. 547, p. 8735, and No. 384, p. 6127; Biography in Saavedra’s Revista, etc., for 1876; Noad’s Manual, pp. 747 and 748; Shaffner, Manual, p. 135; Turnbull, El. Mag. Tel., 1853, pp. 21, 22, 220; Du Moncel, Exposé, Vol. III; “Edinburgh Encyclopædia,” London, 1830, Vol. VIII. p. 535; “Gazette de Madrid” of November 25, 1796; “Mémoires de l’Institut,” Vol. III and “Bulletin de la Soc. Philom.,” An. VI for the new telegraph of MM. Bréguet and Bétancourt, and for the Report made thereon by MM. Lagrange, Laplace and others.
A.D. 1795.—Ewing (John), D.D., Provost of the University of Pennsylvania and one of the founders of the American Philosophical Society, makes a compilation of his course of lectures on natural experimental philosophy, which is subsequently revised for the press by Prof. Robert Patterson.
He devotes much attention to atmospheric electricity, detailing the Franklinian theory, and, besides reporting upon the hypotheses advanced by Henry Eales (at A.D. 1755), as well as treating of the attraction of magnetism, he gives a very interesting account of experiments with the torpedo and the gymnotus electricus. He says that Mr. Walsh found the torpedo “possessed of the power of shocking only in two parts of its body, directly opposite to each other and near to the head. A spot on the back and another on the belly opposite to the former being of a different colour led him to make the experiment, and he found that the electrical virtue was confined to these, and that any other part of the fish might be handled, without receiving a shock, while it was out of the water. Either of these places separately might be handled without the shock being received until a communication between them was formed. This makes it appear probable that the same may also be the case with the Guiana eel. One of these spots must therefore be always in the positive and the other in the negative state; or, rather, they are both generally in the natural state, until, by an effort of the fish’s will, they are suddenly put into different states, as we frequently found that the hand might be in the water, which formed the communication, without receiving any shock. This cannot be the case with the Leyden bottle when charged, which suddenly discharges itself upon forming the communication. Whether there be any electric atmosphere round these spots in the torpedo we cannot tell, as we had no opportunity of examining this matter in the eel, nor have we heard whether Mr. Walsh made any experiments for ascertaining this.”
Electricity of the Atmosphere
The investigations of John Ewing concerning atmospheric electricity were in reality quite extensive. He not only repeated the experiments of Franklin, but he examined thoroughly those of other scientists in the same channel, especially the investigations of Henry Eeles, which will be found detailed in the latter’s “Trinity College Lectures” as well as in his “Philosophical Essays,” London, 1771.
For a very interesting historical review of theories as to the origin of atmospherical electricity, it would be well to consult M. A. B. Chauveau’s article in “Ciel et Terre,” Bruxelles, March 1, 1903, and also Humboldt’s “Cosmos,” London, 1849, Vol. I. pp. 342–346. In the last-named work are cited: Arago, “Annuaire,” 1838, pp. 246, 249–266, 268–279, 388–391; Becquerel, “Traité de l’Electricité,” Vol. IV. p. 107; De la Rive, “Essai Historique,” p. 140; Duprez, “Sur l’électricité de l’air,” Bruxelles, 1844, pp. 56–61; Gay-Lussac, “Ann. de Ch. et de Phys.,” Vol. VIII. p. 167; Peltierin, “Ann. de Chimie,” Vol. LXV. p. 330, also in “Comptes Rendus,” Vol. XII. p. 307; Pouillet, “Ann. de Chimie,” Vol. XXXV. p. 405.
| Date | Name | Experiments | References |
| 1751 | Franklin | Effects of lightning | Phil. Trans., xlvii. p. 289 |
| 1751 | Mazeas | Kite experiments independently of Franklin | Phil. Trans., 1751–1753 |
| 1752 | Nollet | Theory of Electricity | Recher. sur les causes, 1749–1754 |
| Lettres sur l’élect., 1753, 1760, 1767, 1770 | |||
| 1752 | Watson | Electricity of clouds | Phil. Trans., 1751, 1752 |
| 1752 | De Lor and Buffon | Iron pole 99 ft. high, mounted on a cake of resin 2 ft. sq., 3 in. high, Estrapade, May 18, 1752 | Letter of Abbé Mazeas, dated St. Germain, May 20, 1742 |
| 1752 | D’Alibard | Sparks from thunder clouds, 40 ft. pole in garden at Marly, also wooden pole 30 ft. high, at Hôtel de Noailles | Mem. l’Acad., r. des Sci., May 13, 1762 Hist. Abrégée, 1776 |
| 1752 | Le Monnier | Observations of air charge | Mém. de Paris, 1752, pp. 8, 233 |
| 1752 | De Romas | Observations of air charge; kite experiments | Mém. Sav. Etrangers, 1752, and Mém. de Math., 1755, 1763 |
| 1752 | Mylius, Ch. | Observations of air charge | “Nachrichten,” Berlin, 1752 |
| 1752 | Kinnersley | Observations of air charge | Franklin’s Letters, Phil. Trans., 1763, 1773 |
| 1752 | Ludolf and Mylius | Observations of air charge | Letter to Watson |
| 1753 | Richman | Electrical gnomon | Phil. Trans., 1753 |
| 1753 | Canton | Electricity of clouds | Franklin’s letters and Phil. Trans., 1753 |
| 1753 | Beccaria, C.B. | Systematic observations with an electroscope | Lett. dell’ Elet. Bologna, 1758 |
| 1753 | Wilson | Experiments | Phil. Trans., 1753, p. 347 |
| 1754 | Lining | Kite experiments | Letter to Chas. Pinckney |
| 1755 | Le Roy | Experiments | Mém. de Paris, 1755 |
| 1756 | Van Musschenbroek | Kite experiments | Intro. ad Phil. Nat., 1762 |
| 1759 | Hartmann | Origin of electricity | Verbesseter ... Blitzes (Hamb. Mag. vol. xxiv.) |
| 1769 | Cotte | Memoirs on meteorology | Journ. Phys., xxiii., 1783 |
| Mém. Paris, 1769–1772 | |||
| 1772 | Ronayne | Fog observations | Phil. Trans., 1772, p. 137 |
| 1772 | Henley | Quadrant electrometer | Phil. Trans., 1772–1774 |
| 1775 | Cavallo | Fogs, snow, clouds and rain; kite experiments | Treatise on Elect., 1777 |
| 1784 | De Saussure | Observations | “Voyages dans les Alpes,” Geneva, 1779–1796 |
| 1786–7 | Mann | Daily observations with an electrical machine, timing the revolutions to produce a given spark with a record of the weather | Ephémer. Météorol. of the Mannheim Society, 1786–1792 |
| 1788 | Volta | New electroscope | Lettere Sulla Meteor, 1788–1790 |
| 1788 | Crosse | Experiments with collectors | Gilb. Ann., Bd. 41, s. 60 |
| 1791 | Read | Insulation and conductors | Phil. Trans., 1791 and Summary, 1793 |
| 1792 | Von Heller | Observations | Gren, “Neues Journ. der Phys.,” vol. ii. 1795 and vol. iv. 1797 |
| 1792 | Schubler | Observations with weather rod | J. de Phys., lxxxiii. 184 |
An attractive table, which we are permitted to rearrange and reproduce here, giving a résumé of references to some of the most noted experiments of the chief investigators from the time of Franklin to the end of the eighteenth century, was made up by Mr. Alex. McAdie and first appeared in the “Amer. Meteor. Journal.” Mr. McAdie says that a detailed history of most of Franklin’s co-labourers will be found in the accounts given by Exner,[53] Hoppe,[54] Mendenhall,[55] Elster and Geitel[56] as well as by himself,[57] and that in making up this table he has passed over Peter Collinson, of London, who introduced to the notice of the Royal Society the experiments of Franklin, and the three less-known workers—J. H. Winkler, who wrote in 1746 on the electrical origin of the weather lights; Maffei, 1747; and Barberet, 1750.
A.D. 1795.—The telegraphs of the Rev. J. Gamble, Chaplain to the Duke of York, consisted either of five boards placed one above the other or of arms pivoted at the top of a post upon one axis and capable of producing as many signals as there are permutations in the number five, all of the combinations being possible at equal angles of forty-five degrees. His doubts as to the practicability of employing electricity “as the vehicle of information” are fully expressed at p. 73 of his “Essay on the Different Modes of Communicating by Signal,” etc., London, 1797.
References.—J. Gamble, “Observations on Telegraphic Experiments,” etc.; Article “Telegraph” in Tomlinson’s “Encyl. of Useful Arts”; “Penny Ency.,” Vol. XXIV. pp. 147 and 148; “English Cyclopædia,” “Arts and Sciences,” Vol. VIII. p. 66.